The present invention relates to improvements in the fastening of heat sinks both with electronic components and with printed circuit boards, and, in one particular aspect, to unique and advantageous combinations of semiconductor devices, or the like, with auxiliary heat sinks by way of fastening provisions which unite them as readily-processed sub-assemblies and afford wave-solderable surfaces and spacings for convenient mountings on and connections with printed-circuit boards.
Miniature electronic semiconductor devices and circuit modules cannot be responsibly designed into power-handling applications beyond those in which they can successfully expel and prevent excessive build-up of self-generated heat. However, the uses of standard low-cost forms of such items often can nevertheless be significantly extended and enlarged with the aid of small finned metal extrusions or stampings which will adequately conduct and radiate heat away from their thermally-vulnerable regions. Commonly, such heat-sinked items must also be integrated into mechanical and electrical associations with other components, and with electrically-conductive paths, which are disposed on or as part of printed circuitry wherein a relatively sturdy stiff or somewhat flexible insulating "board" or sheet serves as the base or mount. In those instances, economic considerations tend to suggest that use of the heat sinks preferably ought not to complicate or delay or compound the soldering, and that there should be as little as possible of operator involvement and of the handling of separate parts. Moreover, the heat-sinking provisions should be mountable to avoid unintended mechanical, thermal and electrical interactions with the printed circuitry and components.
It has been a well-known practice to spring-clip miniature heat sinks onto small semiconductor devices (U.S. Pat. Nos. 3,572,428 and 4,012,769) and such devices have commonly been soldered securely into place, via their electrical leads, on printed-circuit boards, with their heat sinks clipped on top (U.S. Pat. No. 3,247,896). Further, a tab from such a heat sink has been utilized to make a separate soldered connection with the board, and to promote thermal and electrical contacting (U.S. Pat. No. 3,222,580). In other instances, heat sinks have been bolted to the flanges of semiconductor devices, and it has also been known to stake solderable threaded studs to the heat sinks so that they might at one end be fixed with such devices by way of a nut and then be soldered to printed circuit boards at their opposite ends.